1. Field of the Invention
The present invention relates to a circuit structure, and more particularly, to a circuit structure having a fine circuit.
2. Description of Related Art
Currently, with the rapid advancement of the fabrication techniques of the electronic industry, the circuit boards capable of carrying various electronic components are widely applied in the electronic products with various functionalities. Recently, the electronic products are developed with a trend toward multi-functional and small. Under this trend, it is necessary to increase the layout density of the circuit board to carry a lot of high-precision electronic components. Furthermore, the increasing of the layout density of the circuit board can be achieved by decreasing the line width and the line pitch.
In the conventional techniques, the method for forming the circuit layer comprises entirely electroplating a metal layer on the substrate and then patterning the metal layer by using the photolithography. However, the conventional techniques are limited by the uniformity of the metal layer formed by the electroplating process and the precision of the photolithography process. Hence, it is hard to fabricate the circuit with the line width smaller than 40 micrometers. Thus, the product yield is poor and the cost is high.